Septic arthritis of a lumbar facet joint associated with epidural and paraspinal abscess.

CASE REPORT A 59-year-old woman presented to our clinic two days after experiencing an onset of severe low back pain. There was no prior trauma or other known causal factor. The initial medical examination revealed no neurological abnormalities except for tenderness in her right lumbar region and a positive right Kemp sign. The patient had not developed a fever. Despite taking anti-inflammatory drugs, her low back pain continued. She was admitted 2 days after her initial visit. She had no history of spinal injections or history of diabetes mellitus. Her blood test showed that the inflammatory signs were high, the leukocyte count was 12.200/mm3 (normal range: 4.5008.500/mm3), the erythrocyte sedimentation rate was 84 mm/hr (normal: 3-15 mm/hr) and the C-reactive protein was 5.3 mg/dL (normal: 0.6 mg/dL). Plain radiographs showed no abnormal lumbar vertebrae or facet joint. A T1-weighted sagittal magnetic resonance imaging (MRI) revealed a cystic lesion on the posterior side of the spinal canal at the L2-L3 level (Figure 1). The cystic lesion showed high-signal intensity on T2-weighted axial MRI and it was observed in the epidural and paraspinal regions, communicating with the right L2-L3 facet joint (Figure 2). T1-weighted gadolinium-enhanced contrast was also noted with this lesion. There was no evidence of infection in the vertebral body or disk (Figure 3). Computed tomography scans showed swollen right paraspinal muscles, but no clear damage of the facet joint was observed. The patient’s temperature remained normal, but her C-reactive protein level increased to as high as 19.5 mg/dL 4 days after admission, and she was diagnosed as having septic arthritis of the lumbar facet joint associated with epidural and paraspinal abscess. After intravenous piperacillin sodium administration, the C-reactive protein level temporarily decreased, but her pain worsened. Three weeks later, she still had a fever that reached 38°C. Although no blood cultures showed growth, after continuous intravenous administration of sulbactam sodium/cefoperazon sodium, cefmetazole sodium, and imipenem/cilastatin sodium, her pain became intolerable; therefore, irrigation and debridement were performed 35 days after initial admission to our hospital. The L1-L3 was approached posteriorly and an abcess was noted under the multifidus muscle. The necrotic muscle was removed. The articular capsule and cartilage of the right L2L3 facet joint were debrided. An L1-L3 laminectomy was performed to drain the epidural abscess. Intraoperative cultures revealed no growth. After surgery, the low back pain resolved, and the patient did not report any recurrence at 18-month final follow-up.